Electrical generating system



March 17, 1931. E. x. SCHMIDT ET AL 1,796,810

ELECTRICAL GENERATING SYSTEM Filed No v. 2. 1929 UNIT NO. 1 L mm" m. .2

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Patented Mar. 17, 1931 nairso STATES PATENT OFFIQLE CGEEORATION OFDELAWARE- "\T X. SCI-IIMIDT, OF WHITEFISH BAY, WALTER O. BAER, OFIEILW'AUKEE, .LECSNSIN, ASSIGNORS TO CUTLER-HAMMER, INC, OF IJIL'WAUKEE,'WISCOHSIN, A

ELECTRICAL GENERATING SYSTEM Application filed November 2, 1929. SerialNo. 404,488.

Another object is to provide a controller of the aforesaid characterwhich provides for automatic stopping of either generator unit uponstarting of the other generator Various other objects and advantages ofthe invention will hereinafter appear.

T e acconi anying drawing illustrates a 7 seem embodying the invention"l now be described, it being underiia he system illustrated issuscepti- .iiication without departing from nirit and scope of theappended claims.

lrawing 1 schematically illustrates an autoontrol system embodying theinven- 2 din grammatically illustrates a preform of starter which 1semployed in corn ection w th each of the as en ine drivon units shown inFig. 1, and

2:1 an across-the-line diagram illus- 01 elements shown in Fig. l. ill-gto Fig. 1 the same illustrates a L J small generator unit 1 and a lar egenerator unit 9., each of which includes a generator G in ernalcombustion engine E for O e same. Each of said units is pro- "tii astarter S, and as hereinafter a controller G cooperates with the torender the small unit 1 operaly current to service mains in or lightload conditions and to large unit 2 operative to supply ti" the circuitconnections of certain of' current to said service mains when the loadexceeds the capacity of said former unit. Also as hereinafter set forthcontroller C cooperates with the starters S of units 1 and 2 to effectstopping of either generator unit upon starting of the other generatorunit.

Generators G of the units 1 and 2 are of the same type, and as shown inFig. 2 each is provided with an armature A, series field windings F andF and a shunt field wind ing F lso as shown in Fig. 2 each of saidgenerators is provided with a starter including a starting switch 5 anda main switch 6. Starting switch 5 provides for connection of thegenerator to a storage battery B for operation thereof as a motor forcranking of the engine, and as hereinafter set forth said startingswitch is controlled through the medium of a normally open relay 7, anormally closed governor operated switch 8, and normally closedauxiliary contacts 6 associated with main switch 6. Relay 7 is providedwith normally closed auxiliary contacts 7 for closing a magneto groundcircuit 9 for the engine and said relay is provided with a shunt winding7 and a series winding 7 Main switch 6 provides for connection ofgenerator G to mains Z and Z and the same is provided with a shuntwinding 6 and a series winding 6. Main switch 6 is also provided withnormally open auxiliary contacts (i for establishing a charging circuitfor the battery B through a resistance r.

The above described starter functions and operates in the followingmanner. An automatic start is made by connecting a load across the mainsZ -Z Upon connection of a load across said mains circuit is establishedfrom thenegative side of battery B through the series winding 7 of relay7 to main Z thence through the load to main K through the shunt winding7 of relay 7 and through resistance r to the positive side of battery B.WVinding 7 effects response of relay 7 and said relay in respondingremoves the ground connection GR from the magneto of the engine andestablishes an energizing circuit for starting switch 5 exgizing circuitfor starting switch 5.

switch 5 and through the series field F to the right hand terminal ofsaid armature. The generator G then operates as a motor to crank theenglne E.

It will be observed from Fig. .2 thatthe winding 6 of main switch 6 isconnected across the armature A and series field winding F? and when theengine functions to drive the generator, current is supplied to saidwinding to effect response of main switch 6. Main switch 6 in respondinginterrupts the aforedescribed energizing circuit for starting switch 5extending through auxiliary contacts 6 and establishes circuit from theright hand terminal of the armsture A through series field winding Fthrough winding 6 to main Z whereby the load connected across mains Z -Zis supplied with current by generator G. Also upon response of mainswitch 6 the auxiliary contacts 6 thereof establish a charging circuitfor battery B through the medium of resistance r. Winding 6 holds switch6 in closed position as long as .a load is connected across mains Z Zand upon removal of such load said winding is deenergized to permitopening of main switch. 6.

As aforestated starting switch 5 is energized through the medium of thegovernor operated switch 8. When the generator operates at a speed inexcess of its cranking speed switch 8 opens to interrupt the ener- Thusshould the load be removed from mains Z Z and reconnected thereto beforethe engine speed is reduced below cranking speed the open governorswitch 8 prevents closing of the motor starting circuit unnecessarilyand so avoids a direct connection between the battery and the generatorterminals while the generator is developing its higher voltage.

From the foregoing it will be observed that the starter illustrated inFig. 2 pro vides for automatic starting of the generator unit uponconnection of a load across the supply mains and for automatic stop pingthereof upon removal of the load.

The controller C as shown in Fig. 1 includes an electroresponsive switch10 which is provided with normally closed contacts 10 for connecting themains ofthe small generator unit 1 to the service mains L L? andnormally open contacts 10 for connecting the mainsof the large generatorunit. to said load circuit. The

change-over unit set forth.

provioed Relay 11 as shown in Fig. 1 is normally with a movable contactmember engaging a contact 11 and movable into engagement with a contact11 Said relay is provided with a pair of series operating windings 11and 11 and a shunt holding winding 11 Relay 12 is normally closed and isprovided with a shunt operating winding 12 while relay 13 is normallyopen and is provided with a shunt operating winding 13 Also as shown inFig. 1 the change-over switch 10 is provided with normally openauxiliary con acts 1O? and normally closed auxiliary contacts 10, thelatter contacts being adapted to open following closure of the contacts10*. a

The function and operation of controller C and the cirr i't connectionstherefor will now be more fullydescribed in connection with 3. ins snownin this figure the and 2 are permanently main L an with knife handposition main Z ted to service main L of contacts 10 of transof unit 1through tl fer switcn 10 and windings 11and 11 of relay 11. It is thusapparent that if one of the switches LS 1s closed-to connect a loadacross service mains L L the small generator unit remains in operat onas long as the loel on service mains Eff-L does not exceed the capacityof said unit.

When the load connected across service mains Il L exceeds the capacityof the small generator unit 1, relay 11 responds under the action of itswindings 11 and 11. Upon response of relay llthe winding 11 of saidrelay is connected across mains We? of the large generator unit throughthe medium of auxiliary contacts 10 of transfer switch 10 and thecontacts 11 of said relay. Also upon responsev of relay 11 the operatinwinding 10 of transfer switch 10 is con nected across mains Z -Z of thelarge generator unit through the medium of relay 12 and contacts 113 ofrelay-11. (loil 11 is of relatively lowresistance and upon connectionthereof across mains Z Z said coil acts as a load on the large generatorunit 2 to effect starting of said u t as described in connection with 2.When the voltage across the mains Z Z of the large generator 2 reaches apredetermined value wind- 10 effects response of transfer switch 10 andthe service main L is disconnected from main Z of ti e small generatorunit 1 by marl by winding 11 as long as ti transfer 01 ening of contacts10 and is connected to main Z of the large generator unit 2 by clo sureof contacts 10 Upon disconnection of tee load ii the small generatorunit 1 the same steps as set forth in connection with 2 J c loadconnected across the service nia' Li -L is then supplied with current bythe large generator unit 2. Upon opening oi contacts 10 of the transferswitch the windings l1 and 11 of relay 11 are lie-energized but saidrelay is then held in its operated position by its winding li which ienergiL-ied as hercinbefore described. Upon cl of contacts 10 of thetransfer switch the auxiliary contacts 10 or said switch open tointerrupt the energizing cir cult for winding 11 and relay 11 is thenheld in its operated position by its winding 11 which now carries theentire lead cur rent. Transfer switch 10 in responding establishes amaintaining circuit for itself extending through its auxiliary contacts10 and the relay 12.

Relay 11 is held in its operated position. e current demand exceeds thecapacity of the small generator unit 1. However, w rent demand decreasesto a less than the capacity of the small '3ir3l'Et e) tor unit 1 relay11 drops out and connects the operating winding 13 of the mains oi thelarge generator unit 52 through the medium of the auxiliary contacts 10of transfer switch 10. Relay 13 then responds to connect the operatingwinin 12 frelay 12 across the mains /'tor the small generator unit 1 inparallel with a resistance Resistance 7 and coil. 12 of relay 12 act asa load across the mains Z-Z of the small generator unit and said unit isthen started as hereinbetore set forth. ll hen the voltage across mainsZ Z of the small generator unit 1 builds up to a given value winding 12oi? relay effects response of said relay to interrupt the aforedescribedenergizing circuit for switch 10. Transfer switch 10 then returns tonormal position to re-conncct the load on the ser ice mains LL to thesmall generator unit 1. As set forth in connection w h 2 the generatorunits are aut matically stopped under no load conditions. Thus uponreturn or" transfer switch 10 to normal position the large generatorunit 2 stopped and the small generator unit 1 remains in operation aslong there is current demand or until the current demand exceeds thecapacity thereof. I

IV hen lzniiie switch 14: is moved into right hand position the smallgenerator unit 1 is rendered inoperative since the service main I isthen connected to main Z of the large generator unit However, as isapparent from the description in connection with Fig. 2 the largegenerator unit 2 is then operative to supply current to the servicemains L L upon connection of a load across the same.

lVhat we claim as new and desire to secure by Letters Patent is:

1. In a system of electrical distribution, in combination, two generatorunits of different capacities, separate means for starting each of saidunits upon current demand across the mains thereof, a load circuitnormally connected to the mains of the smaller of said units, means forstarting the larger of said units when the currentv supplied by saidsmaller unit to said load circuit exceeds a given Value and means actingupon starting of said larger unit to connect the mains thereof to saidload circuit and to disconnect themains of said smaller unit from saidload circuit.

2. In a system of elec rical distribution, in combination, two generatorunits of different capacities, separate means for starting each of saidunits'upon current demand across the mains thereof, a load circuit normally connected across the mains of the smaller or" said units, meansfor starting the larger of said units when the current supplied by saidsmaller unit to said load circuit exceeds a given value, means actingupon starting of said larger unit to connect the mains thereof to saidload circuit and disconnect the mains of said smaller unit from saidload circuit, means for restarting said smaller unit when the currentsupplied by said larger generator unit is loss than the capacity of saidsmaller unit and means acting upon restarting of said smaller unit toreconnect the mains thereof to said load circuit and to disconnectthe/mains of said larger unit from said load circuit.

3. In a system of electrical distribution, in combination, twogas-engine-operated generating units of dilierent capacities, a com: monload circuitnormally connected to the smaller of said units, means forstarting the smaller of said generator units upon current demand in saidload circuit, means for starting the larger of said generator units whenthe current supplied by said smaller unit to said load circuit exceeds agiven value, and means responsive to a given volt age across the mainsof said larger unit for disconnecting said load circuit from saidsmaller unit and for connecting said load circuit to the mains of saidlarger unit.

4. In a system of electrical distribution, in combination, twogas-engine-driven generating units of different capacities, a common'load circuit to be supplied thereby, separate means for starting each ofsaid units upon current demand across the mains thereof, anelectromagnetic switch normally connecting said load circuit across themains of the smaller of said units and responsive to a given voltageacross the mains oi the larger of said units to disconnect said loadcircuit froin rsaid smaller unit and to connect the same totlie mains ofsaid larger unit, and means for starting the larger of said generatorunits when the current supplied by the smaller of said generator unitsto said load circuit exceeds a given value.

5. In a system of electrical distribution, in combination, twogasengine-operated generating units of diilerent capacities, a commonwork circuit to be supplied thereby, an automatic controller associatedwith each of said units for starting the same upon current demand acrossthe mains thereof, a switch normally connecting said work circuit to thesmaller of said generatorunits and responsive upon given currentconditions across the mains oi the larger of said units to disconnectsaid work circuit from said smaller unit and to connect the same to saidlarger unit, means for starting said larger unit when the currentsupplied by said smaller unitexceeds a given value, said means includinga relay responsive to given current conditions in said load circuit toeiiiect loading of said larger unit tor-"starting thereof. r

6. In a system of electrical distribution, in combination, twogas-engine-operated generating units of different capacities, a commonwork circuit to be supplied thereby, an automatic controller associatedwith each of said units for starting the same upon current demand acrossthe mains thereof, a switch normally in a position to connect said Workcircuit to the smaller of said generator units and responsive upon givencurrent conditions across the mains of the larger 01" said units todisconnect said work circuit from said smaller unit and to connect thesame to said larger unit, means including a relay responsive to givencurrent conditions across the mains of said smaller unit to effectstarting of said larger unit, and means including a relay for startingsaio smaller unit when the current supplied by said larger unit to saidload circuit is below a given value.

7. In a system of electrical distribution, in combination, twogas-engine-operated generating units of ditlerent capacities, a commonwork circuit to be supplied thereby, an automatic controller associatedwitheach of said units for starting the same upon cur rent demand acrossthe mains thereof, a switch normally connecting said work circuit to thesmaller of said generator units and responsive upon given currentconditions across the mains of the larger of said generator units todisconnect said work circuit from said smaller unit and to connect thesame to said larger unit, means responsive to given current conditionsin said load circuit to effect loading of said larger unit startingthereof.

In witness whereof, we have hereunto subscribed our names.

EDWIN X. SCHMIDT. WALTER O. BAER.

